The normal value of blood calcium is 2.25-2.75 mmol/L. Hypocalcemia is defined as hypocalcemia when blood calcium is lower than 2.25 mmol/L. Calcium ions can reduce the excitability of the nervous system. The most important clinical symptoms of hypocalcemia are as follows: i. Increased excitability of the nervous system, hypocalcemia can occur with muscle spasms, and in severe cases, hypocalcemic convulsions, which can involve the nervous system with irritability and cognitive impairment. Second, the cardiovascular system can occur arrhythmia, and even heart failure. Third, long-term hypocalcemia can affect the development of the skeletal system, manifested as bone pain, pathological fractures, bone softening, osteoporosis, fibrocystic osteitis, etc.. Low calcium can also cause dry skin, thinning hair, etc. Fourth, severe hypocalcemia can occur hypocalcemia crisis, hypocalcemia crisis can endanger the patient’s life, need to actively deal with.